2016/02/21 by Merry Mani, Mathews Jacob, Mani, Merry +6
Physics and Astronomy · Medicine · #Advanced X-ray Imaging Techniques #Advanced Neuroimaging Techniques and Applications #Advanced MRI Techniques and Applications
paper · pdf · doi:10.48550/arxiv.1602.07274
Purpose: To introduce a novel method for the recovery of multi-shot diffusion\nweighted (MS-DW) images from echo-planar imaging (EPI) acquisitions.\n Methods: Current EPI-based MS-DW reconstruction methods rely on the explicit\nestimation of the motion- induced phase maps to recover the unaliased images.\nIn the new formulation, the k-space data of the unaliased DWI is recovered\nusing a structured low-rank matrix completion scheme, which does not require\nexplicit estimation of the phase maps. The structured matrix is obtained as the\nlifting of the multi-shot data. The smooth phase-modulations between shots\nmanifest as null-space vectors of this matrix, which implies that the\nstructured matrix is low-rank. The missing entries of the structured matrix are\nfilled in using a nuclear-norm minimization algorithm subject to the\ndata-consistency. The formulation enables the natural introduction of\nsmoothness regularization, thus enabling implicit motion-compensated recovery\nof fully-sampled as well as under-sampled MS-DW data.\n Results: Our experiments on in-vivo data show effective removal of the\nghosting artifacts arising from intershot motion in MS-DW data using the\nproposed method. The performance is comparable and better in certain cases than\nconventional phase-based methods.\n Conclusion: The proposed method can achieve effective unaliasing of\nfully/under-sampled MS-DW images without using explicit phase estimates.\n